/*
  This exmple program provides a trivial server program that listens for TCP
  connections on port 9995.  When they arrive, it writes a short message to
  each client connection, and closes each connection once it is flushed.

  Where possible, it exits cleanly in response to a SIGINT (ctrl-c).
*/


#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#ifndef _WIN32
#include <netinet/in.h>
# ifdef _XOPEN_SOURCE_EXTENDED
#  include <arpa/inet.h>
# endif
#include <sys/socket.h>
#endif

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

static const char MESSAGE[] = "Hello, World!\n";

static const int PORT = 9995;
class CallbackSet {
 public:
  static void listener_cb(struct evconnlistener *, evutil_socket_t,
                          struct sockaddr *, int socklen, void *);
  static void conn_writecb(struct bufferevent *, void *);
  static void conn_eventcb(struct bufferevent *, short, void *);
  static void signal_cb(evutil_socket_t, short, void *);
};

int main(int argc, char **argv) {
  struct event_base *base;
  struct evconnlistener *listener;
  struct event *signal_event;

  struct sockaddr_in sin;
#ifdef _WIN32
  WSADATA wsa_data;
  WSAStartup(0x0201, &wsa_data);
#endif

  base = event_base_new();
  if (!base) {
    fprintf(stderr, "Could not initialize libevent!\n");
    return 1;
  }

  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  sin.sin_port = htons(PORT);

  listener = evconnlistener_new_bind(base,
                                     CallbackSet::listener_cb,
                                     (void *)base,
                                     LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE,
                                     -1,
                                     (struct sockaddr*)&sin,
                                     sizeof(sin));

  if (!listener) {
    fprintf(stderr, "Could not create a listener!\n");
    return 1;
  }

  signal_event = evsignal_new(base,
                              SIGINT,
                              CallbackSet::signal_cb,
                              (void *)base);

  if (!signal_event || event_add(signal_event, NULL)<0) {
    fprintf(stderr, "Could not create/add a signal event!\n");
    return 1;
  }

  event_base_dispatch(base);

  evconnlistener_free(listener);
  event_free(signal_event);
  event_base_free(base);

  printf("done\n");
  return 0;
}

void CallbackSet::listener_cb(struct evconnlistener *listener,
                              evutil_socket_t fd,
                              struct sockaddr *sa,
                              int socklen,
                              void *user_data) {
  struct event_base *base = (struct event_base *)user_data;
  struct bufferevent *bev;

  bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
  if (!bev) {
    fprintf(stderr, "Error constructing bufferevent!");
    event_base_loopbreak(base);
    return;
  }
  bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL);
  bufferevent_enable(bev, EV_WRITE);
  bufferevent_disable(bev, EV_READ);

  bufferevent_write(bev, MESSAGE, strlen(MESSAGE));
}

void CallbackSet::conn_writecb(struct bufferevent *bev,
                               void *user_data) {
  struct evbuffer *output = bufferevent_get_output(bev);
  if (evbuffer_get_length(output) == 0) {
    printf("flushed answer\n");
    bufferevent_free(bev);
  }
}

void CallbackSet::conn_eventcb(struct bufferevent *bev,
                               short events,
                               void *user_data) {
  if (events & BEV_EVENT_EOF) {
    printf("Connection closed.\n");
  } else if (events & BEV_EVENT_ERROR) {
    printf("Got an error on the connection: %s\n",
           strerror(errno));/*XXX win32*/
  }
  /* None of the other events can happen here, since we haven't enabled
   * timeouts */
  bufferevent_free(bev);
}

void CallbackSet::signal_cb(evutil_socket_t sig,
                            short events,
                            void *user_data) {
  struct event_base *base = (struct event_base *)user_data;
  struct timeval delay = { 2, 0 };

  printf("Caught an interrupt signal; exiting cleanly in two seconds.\n");

  event_base_loopexit(base, &delay);
}
